1. Field of the Invention
The invention, in general, relates to the production of betulinic acid and, more particularly, to a novel method of producing betulinic acid from plant fibers.
2. The Prior Art
Betulinic acid otherwise known as 3b-hydroxy-lup-20(29)-en-28-acid (C.sub.30 H.sub.48 O.sub.3) is a natural substance with a triterpene molecular structure and has been found in many plants. A specific effect of betulinic acid against the growth of cancer cells was described in 1995 by Pisha et al. in Nature Medicine 1, pp. 1046 seq. Amides of betulinic acid have been described as anti-HIV-agents with a new kind of effective mechanism in 1996 by Evers et al. in J. Med. Chem. 39, pp. 1056 seq. and by Soler et al. in J. Med. Chem. 39, pp. 1069 seq. This has led to a substantial increase in the demand for betulinic acid.
Methods of its production, for instance from the bark of picramnia pentandra (simaroubaceae) have been described by Herz et al. in Photochemistry, Vol. 11, 1972, pp. 3061 seq., and, from the bark of arbutus menziesii (ericaceae), by Robinson et al. in Photochemistry, Vol. 9, 1970, pp. 907 seq., and, from the bark of ziziphus Mauritania (rhamnaceae), by Pisha et al. In Nature Medicine, Vol. 1, pp. 1046 seq.
These starter materials are difficult to obtain, however. They require complex isolation processes, as the betulinic acid can be extracted only in admixture with other substances and it constitutes but a small proportion of the total abstract. Its separation requires multiple-stage cleaning by complex procedures, usually chromatographically. Thus, such production of betulinic acid is correspondingly expensive.